@lxs If editing the mesh is too much work for you, you would need to use a different approach for creating outlines: using a screen space (post processing) outline effect. If you e.g. search the Unity Asset Store for outline effect you should find multiple solutions.
Please note that the provided Spine outline shader functionality is not a perfect solution for all use-cases, it's mainly a feature that can easily provide the feature with little performance overhead, but comes with some limitations and skeleton setup requirements.
